Recording-voltmeter



(No Model.) 2 Sheets-Sheetfl. W. H. BRISTOL.

RECORDING VOLTMETER.) No. 505,243. Patented Sept. 19, 1893.

' WITNESSES: INVENTOR J5 lff i4/M WilliamRErisL 0L ATTORNEY UNITEDSTATES WVILLIAM H. BRISTOL, OF

RECORDING- HOBOKEN, NEW JERSEY.

VOLTMETER.

SPECIFICATION forming part of Letters Patent No. 505,243, datedSeptember 19, 1893.

Application filed April 17, 1393.

To all whom it may concern:

Be it known that I, WILLIAM H. BRISTOL, a citizen of the United States,and a resident of Hoboken, in the county of Hudson and State of NewJersey, have invented certain new and useful Improvements in Recording-Voltmeters, of which the following is a specification.

My invention has reference to electrical devices of that characterespecially adapted for employment in galvanometers, volt or ammeters, orsimilar instruments for indicating and recording an electrical currentor the work done thereby.

The nature of my invention and its application to the instruments of theclass above mentioned will best be understood when described inconnection with the accompanying drawings, in which- Figure 1 representsa vertical section in the plane a: 00, Fig. 2, of a voltmeter embodyingmy invention. Fig. 2 is a vertical cross section thereof in the plane yy, Fig. 1. Fig. 3 is a sectional elevation, part being broken away.Figs. 4, 5, 6 and 7 are elevations illustrating modified forms.

Similar letters of reference designate corresponding parts throughoutthe several views of the drawings.

Referring at present to Figs. 1 and 2, where I have illustrated arecording voltmeter, the letters E E designate two stationary solenoids,and A is a movable solenoid arranged between the two former solenoids,the same being moved toward the solenoid E when the several solenoidsare vitalized. The general arrangement of the solenoids with relation toeach other is similar to that of the Thompson electric balance and formsno part of my present invention. The solenoid A is rigidly mounted upona horizontal support or shaft 13, extending freely through the centersof the solenoids E E but not supported by the same. The main portion ofthe shaft consists of an insulating material, such as gutta percha orwood fiber, while its ends b b are made of metal and connectedrespectively with the terminal wires of the movable solenoid A, (Fig.3.) These metallic ends of the shaft B rest in vertical metallicsupports a c secured to posts 0 G projecting from the back D of thecasing; the support 0 being however in- Serial No, 470,640. (No model.)

sulated from its post. The parts 0 c I make quite thin and of aresilient conducting material, so that they form a flexible supportpermitting lateral motion of the solenoid A, while at the same time theyreturn the same to and hold it in its normal position. The solenoidrested in these flexible supports is caused to move in substantially aright line, which fact is of considerable importance. As here shown theends I) b of the shaft B are turned round and formed with grooves whichfit into suitable Vs cut into the supports 0 0, so that the shaft isheld to said supports. The bearings (one or both) may however, be of aknife edge construction, which has the advantage that the shaft isprevented from turning.

To one of the flexible supports (Figs. 1 and 2) is secured a pointerorarm d, which is carried outwardly and upwardly to bring its free endopposite to the zero point of an appropriate scale on a chart P when thesolenoid A is in its normal position. The pointer or arm is providedwith a suitable marking device, such as the pen or style 6, and thechart is rotated by a suitable clock movement M.

F F are binding posts secured to the cover D of the casing. To thethreaded shank of the post F is secured a spring contact platefinsulated from said cover and arranged in contact with a binding screw9 insulated from the back D of the casing. The current ontering at thebinding post F (Fig. 3) passes through the metal of the back D, to post0', from thence over flexible support 0' to the terminal b of thesolenoid A; through the coils of the latter to the terminal I); thenceto flexible support 0; over wire 13 to solenoid E, and from thence bywire 14 to solenoid E; over wire 15 to the binding screw g, and overplate f to binding post F The respective coils of the solenoids are sowound that the solenoids A and E present opposite poles to each otherwhen vitalized, while the solenoids A and E present like poles,andconsequently solenoid A will move toward solenoid E under an increasedand nearly uniform magnetic force,-the distance through which it movesvarying according to the voltage of the current.

It will be noticed that in my present construction I dispense with theordinary iron cores and armatures, in consequence whereof there is nomagnetic lag with a decreasing voltage of the current, and the pointerwill always return to and give the same indication on the chartas withan increasing voltage. The instrument will in all cases give anabsolutely correct indication of the voltage. Of course, if so desired,an instrument embodying electro-magnets could be made, the movableelectro-magnet being mounted on the flexible supports before described.By insulating the opposite ends of the shaft I3 from each other andmaking the same the termmals of the movable solenoid A, which istherefore in electrical connection with the supports 0 c, I avoid theuse of connecting wires which would offer friction and resist ance tothe motion of the solenoid.

It is evident that the instruinentis adapted either for the measurementof direct or alterhating currents provided the proper charts are appliedfor the respective currents. A dynamometer can be constructed on thesame principle by forming the solenoid A of fine wire and the solenoidsE E of coarse wire.

lVith two solenoids and an intermediate movable solenoid, a nearlyuniformly spaced scale is obtained. \Vhen this is not essential, or whenan open scale is desired at either end of the range, I construct theinstrument with but one stationary solenoid, as shown in Fig. 6.According to the nature of the scale desired the solenoids are woundeither to mutually attract or repel.

In place of having the shaft B arranged to pass through the solenoidsEE, the solenoid A may be suspended from a horizontal support B (Fig. 4)arranged above the solenoids and retained in flexible supports 0 c asbefore. Also, the supports 0 0' may be made rigid in themselves andhinged; one of the same being subjected to the action of a suitablespring. Such a construction I have shown in Fig. 5 where c c are thepivoted supporting arms, connected to the shaft or bar B upon which thesolenoid is mounted, and h is the spring which returns the solenoid to,and holds it in its normal position with the aid of a stop h.

To hold the movable solenoid rigid while the instrument is being carriedor transported, any one of the usual devices may be employed, forinstance, as here shown, (Figs. 1 and 2,) a plate j is arranged toengage with and lift the solenoid A against a stop j, when the screw 7'is turned, thereby also lifting the shaft B out of its bearings.

In Fig. 7, I have shown but two solenoids and a modified arrangement ofthe solenoids. In this instance the movable solenoid A is arrangedconcentrically within the stationary solenoid E As in the apparatusshown in Figs. 1 to 3 the solenoid A is mounted upon flexible supports.

It is of course to be understood that instead of connecting thesolenoids in series, as here shown, they could be arranged in parallel,if So desired, to produce a certain total resistance, or they could bewound in any other way to produce any desired resistance.

While in the examples herein illustrated I have shown the movablesolenoid supported from below,it is evident that the movable solenoidcould be suspended in the flexible arms.

hat I claim as new, and desire to secure by Letters Patent, is

1. In an electrical measuring instrument, the combination of astationary solenoid, a movable solenoid provided with metallic portionson its opposite sides insulated from each other and forming theelectrical terminals of the same, and flexible metallic supports inelectrical connection with the metallic portions of the movablesolenoid, substantially as described.

2. In an electrical measuring instrument, the combination of astationary solenoid, a movable solenoid mounted on a horizontal shafthaving metallic ends insulated from each other and connectedrespectively with the terminals of the movable solenoid, and verticalflexible conducting supports provided with recesses in which themetallic ends of the shaft rest to form electrical connection betweensaid supports and the movable solenoid, substantially as described.

3. The combination with the stationary solenoid, of a movable solenoidadapted to the same, a support for the movable solenoid provided withmetallic ends insulated from each other and forming the terminals of themov able solenoid, and conducting supports in which said metallic endsrest, substantially as described.

4:. I11 an electrical measuring instrument, the combination of astationary solenoid, a movable solenoid adapted to the same, swingingconducting supports for the movable solenoid, and an indicating orrecording arm attached directly to one of said supports andparticipating in the angular movements of the same, substantially asdescribed.

Signed at NewYork, in the county of New York and State of New York, this3d day of April, A. D. 1893.

IVILLIAM II. BRISTOL.

\Vitnesses:

KLAS II. Tnnus'rnnr, A. FABER DU FAUR, J r.

